ZyXEL Communications Prestige 650HW - Manual (Page 194)

Prestige 650HW ADSL Router User’s Guide
Wireless LAN and IEEE 802.11 A
Appendix A
Wireless LAN and IEEE 802.11
A wireless LAN (WLAN) provides a flexible data communications system that you can use to access various
services (navigating the Internet, email, printer services, etc.) without the any expensive network cabling
infrastructure. In effect a wireless LAN environment provides you the freedom to stay connected to the
network while in the coverage area.
Benefits of a Wireless LAN
1. Access to network services in areas otherwise hard or expensive to wire, such as historical buildings,
buildings with asbestos materials and classrooms.
2. Doctors and nurses can access a complete patient’s profile on a handheld or notebook computer upon
entering a patient’s room.
3. It allows flexible workgroups a lower total cost of ownership for networks that are frequently
reconfigured.
4. Conference room users can access the network as they move from meeting to meeting- accessing up-to-
date information that facilitates the ability to communicate decisions “on the fly”.
5. It provides campus-wide networking coverage, allowing enterprises the roaming capability to set up
easy-to-use wireless networks that transparently covers an entire campus.
IEEE 802.11
The 1997 completion of the IEEE 802.11 standard for wireless LANs (WLANs) was a first important step in
the evolutionary development of wireless networking technologies. The standard was developed to maximize
interoperability between differing brands of wireless LANs and to introduce a variety of performance
improvements and benefits. On September 16, 1999, the 802.11b provided much higher data rates of up to
11Mbps, while maintaining the 802.11 protocol.
The IEEE 802.11 specifies three different transmission methods for the PHY, the layer responsible for
transferring data between nodes. Two of the methods use spread spectrum RF signals, Direct Sequence
Spread Spectrum (DSSS) and Frequency-Hopping Spread Spectrum (FHSS), in the 2.4 to 2.4825 GHz
unlicensed ISM (Industrial, Scientific and Medical) band. The third method is infrared technology, using
very high frequencies, just below visible light in the electromagnetic spectrum to carry data.